题目描述 You are given an integer sequence of length N, a= {a1,a2,…,aN}, and an integer K. a has N(N+1)⁄2 non-empty contiguous subsequences, {al,al+1,…,ar} (1≤l≤r≤N). Among them, how many have an arithmetic mean that is greater than or equal to K? Constr…